What do you think of my disasterous first attempt?
Thanks for your attempts, we need more BT art!
I think you are doing fine and I am looking forward to more of your works. If I may be so bold as to suggest something although I am not an artist... it may look even better if you emphasize the contour lines a little more. If the source image has a low resultion you may have to do it manually and this is extremely tiresome, but the result could be rewarding. But as I said, I am no artist and might be totally wrong.
Another point I would like to make is more from the in-universe perspective. Military personnel can be quite artsy when it comes to painting military hardware (I saw that myself during my time in the air force), but there are some technical limits: Think about the ground crew with their buckets of paint and their big paintbrush. Such colour gradients like on your Nova Cat's torso are hard work. I think even in the future they'd probably stick to clear cut colours. (I hope I can get my point across; it is a bit difficult for me since I am not only not an artist, I am also not a native speaker).
Please don't take that as negative criticism, I absolutely appreciate your contributions! :)